Currently, memory packages, such as dual, in-line memory modules (DIMM) may reside on both sides of a printed circuit board (PCB) or other substrate, referred to herein as a double-sided DIMM. This increases memory density for the system. Signals for the memories may route through the substrate, which may have several layers. With memory packages on both sides of the substrate, signal routing and integrity may become an issue.
Signals being routed through the substrate may connect to balls or connections to the DIMM on opposite sides of the packages. For example, signals going to the closest side of the package on the one side of the substrate will generally end up having to go to the farthest side of the package on the other side of the substrate. The DIMM for the other side of the package is turned “upside down” to mount it on the other side, causing the relevant connection to be on the other side of the package from the signal origination.
Furthermore, such DIMM devices may include a double data rate (DDR) memory, such as, a synchronous dynamic random access memory (SDRAM). SDRAM is a volatile and complex memory device; that is, when power is removed from an SDRAM device, all contents and operating configurations are lost. Hence, each time an SDRAM device is powered up, the device requires a defined procedure to initialize the internal state machines and to configure various user-defined operating parameters.